CONDE AMIANO , Alejandro

Fe75B20Nb5, Fe75Ge10B10Nb5 and Fe75Ge20Nb5 alloys were prepared by ball milling from pure powders and their microstructure and magnetic properties were studied. A nanocrystalline solid solution of-Fe type is the main phase formed, although traces of some intermetallics were found in the Fe-B-Nb alloy. The local arrangements of Fe atoms in Ge...

A procedure to optimize the isothermal calorimetric data of very slow transformation processes of metastable systems is proposed. The method uses an experimental baseline to identify the transitory effects due to the equipment. Moreover, the combined use of isothermal and non-isothermal results is shown to be effective to overcome the...

Cellular automata simulations have been performed to simulate the crystallization process under a limited growth approximation. This approximation resembles several characteristics exhibited by nanocrystalline microstructures and nanocrystallization kinetics. Avrami exponent decreases from a value n = 4 indicating interface controlled growth...

C25H30N2010, Mr = 518·5, orthorhombic, P2 1212¡, a= 12·303 (2), b =:= 25·071 (4), e=pentyl chain range from 45 to 80°. The crystal cohesion is mainly dueto van der Waa1s interactions 8·823 (5) A, V= 2721·4 (16) Á3 Z = 4, Dx =but there are two possible hydrogen bonds along 1·265 Mgm-, t\(Mo Ka) =0·7107 Á, .=[100] and [001]. ...

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1-(3,5-Dimethyl-3-nitro-1-pyrazolin-4-yl)­ penta-0-acetyl-o-galacto-pentitol, e20H29N 3012, Mr= 503·5, orthorhombic, P21212¡, a= 14·471 (9), b = 14·518 (3), e= 12·028 (2) A, V= 2527·0 (1·7) A3, z = 4, Dx = 1·323 Mg m- 3, .A(Mo Ka)= 0·7107 A, J.L = 0·1O mm- 1, F(OOO) = 1064, room temperature, final wR = 0·035 for 1836 observed...

The influence of composition changes on the devitrification process, microstructure and magnetic properties of (Fe,Co)MoB(Cu) alloys was investigated. Amorphous and nanocrystalline samples were studied by differential scanning calorimetry, thermomagnetic gravimetry, X-ray diffraction, transmission electron microscopy and vibrating sample...

In this work, we propose a model for using the classical Johnson-Mehl-Avrami-Kolmogorov (JMAK) crystallization theory to analyze nanocrystallization processes as a set of multiple microprocesses. This model is based on the well-known microstructure observations of nanocrystalline systems for which, although the number of crystallites increases...

La desvitrificación de la aleación amorfa Fe75Cu2Nb3SÍ2Q 5 B9 5 tiene lugar en dos etapas. El principal resultado de la primera etapa es la nanocristalización, que da lugar a una nanofase cristalina Fe,Si homogéneamente dispersa en la matriz amorfa. Al aumentar la temperatura, el contenido en Si de los nanocristales de Fe,Si disminuye, como...

The temperature dependence of the hysteresis loops of Nanoperm-type alloys has been studied. In the high-temperature region above the coercivity maximum, the response of the system can be modeled as that of dipolar-interaction superparamagnetic particles, considering a mean interaction field. Special attention has been paid to the influence of...

The effect of the Si/B ratio on the magnetic anisotropy distribution of Fe73.5Si22.52xBxCu1Nb3 (x57,9,16) alloys has been studied. The influence of isochronal annealing on the hysteresis loop of the three studied alloys has been analyzed. They present two minima in coercivity: the first one can be ascribed to structural relaxation, and the...

Fe75Nb10B15 alloys were prepared by mechanical alloying using different boron powders (crystalline B, commercial amorphous B, optimized amorphous B and intermetallic FeB) in the initial mixture, in order to study the boron incorporation into the Fe matrix and its influence on the amorphization of the alloys. Another composition with the same...

Fe75Nb10B15 alloys were prepared by mechanical alloying using different boron powders (crystalline B, commercial amorphous B, optimized amorphous B and intermetallic FeB) in the initial mixture, in order to study the boron incorporation into the Fe matrix and its influence on the amorphization of the alloys. Another composition with the same...

The recrystallization process in FeCoNbBCu nanocrystallinealloys is evidenced from thermomagnetic results as a significant decrease in magnetization at the second crystallization stage. The lowering in the volume fraction of α-FeCo crystals indicates that some of these crystals contribute to the boride phases formed. Electron microscopy images...

A Mössbauer spectrometry and magnetic study have been performed on FeCoSiAlGaPCB amorphous alloys in order to get information about the variations in the atomic short range order with the substitution of Fe by Co. The decrease of the Curie temperature with decreasing Fe content was analyzed in the framework of the molecular field theory. The...

The classical theory of Johnson-Mehl-Avrami-Kolmogorov (JMAK) is widely used to describe the kinetics of crystallization even when the premises required for its application are not strictly fulfilled. In this paper we propose a procedure to obtain the JMAK parameters of the independent transformations that simultaneously occur during a...

Multicomponent Fe65.5Cr4Mo4Ga4P12C5B5.5 amorphous alloy is known to have good soft magnetic properties combined with large glass-forming ability. Searching for a nanocrystalline structure that could improve its magnetic properties, Cr and Mo were partially substituted by Cu. The devitrification process of Cu-containing alloys shows an...